OTP Key Register Control for Secure Semiconductor Authentication
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Solution Overview
Problem
Semiconductor devices face security vulnerabilities as non-authorized third parties can access and leak the permanently programmed security keys, compromising the integrity of the authentication process.
Innovation Solution
Incorporating a one-time programmable (OTP) memory device with key protection bits and end-of-life bits to control the loading of secret values, using a key protection control logic that manages access based on the device's life cycle and operational state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a security key is permanently programmed into the chip during fabrication, then the device can execute security software and authentication functions, but the key becomes accessible to non-authorized third parties who can leak the key from the distributed chip
Solution Approach 1:
The patent extracts the security key from permanent OTP memory and places it in a register that can be controlled for loading and clearing. This allows the key to be removed from persistent storage when not in use, preventing third-party access while maintaining authentication functionality. The key is loaded only when needed and cleared when not needed, eliminating the permanent exposure risk.
Solution Approach 2:
The patent introduces dynamic control over key persistence through a register that can transition between loaded and cleared states based on operational conditions. The loading permission signal and control logic enable the system to adaptively manage key availability, making the security mechanism flexible rather than static. This dynamic approach allows the key to be present only when authentication is required.
2Productivity
If the secret value is always loaded into the key register for authentication operations, then authentication functions can be executed efficiently, but the secret value remains exposed and vulnerable to unauthorized access
Solution Approach 1:
The patent implements preliminary loading of the secret value into the key register only when authentication operations are anticipated to be needed. The control logic monitors operational states and loading permission signals to determine when to load the key in advance, preparing the authentication function before it is actually required. This allows efficient authentication when needed while minimizing the time the key is exposed.
Solution Approach 2:
The patent implements a clear mechanism that discards the secret value from the key register when authentication operations complete or when loading permission is revoked. The control logic automatically clears the register under appropriate conditions, removing the exposed key from the system. This cyclical loading and clearing pattern maintains productivity while reducing exposure risk.
3Duration of action of stationary object
If security keys are permanently stored in OTP memory, then the device maintains security functionality throughout its life cycle, but the keys cannot be protected or sanitized after the device reaches end of life
Solution Approach 1:
The patent changes the operational parameters of key storage by introducing state control through loading permission signals and end-of-life detection. The system transitions from a static permanent storage model to a dynamic controlled access model. When end-of-life conditions are detected, the control logic changes the loading permission parameter to prevent further key loading, effectively sanitizing the device while maintaining functionality during its operational life.
Solution Approach 2:
The patent implements feedback mechanisms where the control logic continuously monitors operational state and loading permission signals to determine key loading decisions. The system receives feedback about its own operational status and adjusts key management accordingly. This feedback loop enables automatic key clearing when end-of-life conditions are detected, providing security protection throughout the device lifecycle including post-deployment phases.
Data Source
AI summary
A semiconductor device includes a one-time programmable (OTP) memory device, a key register and a key protection control logic. The OTP memory device stores a secret value, a key protection bit indicating whether to protect the secret value, and an end of life bit indicating whether to discard the semiconductor device. The key register loads the secret value from the OTP memory device and stores the secret value. The key protection control logic controls loading of the secret value from the OTP memory device to the key register based on the key protection bit and the end of life bit. Security of the secret value is enhanced and utilization of the secret value is optimized using the key protection bit and the end of life bit.